Windshield wiper system



Sept. 9, 1952 R. FREEDMAN ET Al. 2,609,795

wINnsHIELD wIPER SYSTEM Filed Oct. 4, 1945 HTToR/VEKS.

Patented Sept. 9, 1952 t 2,609,795 Y WINDSHIELD WIPER SYSTEM Rudolph Freedman, University City, and John E.

Dube, Chesterfield, Mo., assignors,`by mesne ast sigments, to Alco Valve Co., St. Louis, Mo., a corporation ofMissouri Application October 4, 1945, Serial N o. 620,316

6 Claims.

This invention pertains to improvements in hydraulic windshield wipers and concerns itself primarily with improved apparatus providing for the parking of the wiper blades automatically.

It is a general aim of the invention to provide a hydraulic windshield wiper device having means for moving a wiper blade to a selected position automatically and maintaining the blade in this position when the device is not operating.

More specifically, it is an object of the invention to provide a hydraulic windshield wiper device having aspeed control valve capable of controlling the ilow of iluid to its wiper units in a manner such as to move the blades of the wiper units to a selected position automatically and maintain them in this position, commonly referred to as their parked or parking position.

Another object of the invention is to provide a hydraulic Windshield Wiper system with an improved speed control valve `automatically operable, upon movement to stop the systems wiper units, to move the wiper blades to a parked position.

It is a further object of the invention to provide an improved speed control valve for a hydraulic windshield wiper system having. in addition to a metering valve, a parking valve operable upon the closing of the former to supply fluid to a wiper unit line of the system so as to automatically move the respective wiper blades to a parked position. I

A still further object of the invention is to provide an improved hydraulic windshield wiper system having means operable to bypass Vfluid around the systems control unit to a wiper unit line upon initial stoppage of fluid to the control unit.

Other objects and advantages will become apparent as the description proceeds, and a more comprehensive understanding of the invention will be afforded from the following detailed description when considered in conjunction with the accompanying drawing, in which: Fig. 1 is a plan view of a hydraulic windshield wiper system embodying the instant invention;

Fig. 2 is a side elevational view of a speed control valve employed in the Vsystem illustrated in Fig. 1 taken along the line 2-'2 thereof;

Figs. 3 and 4 are vertical sectional views of the lspeed control valve shown in Fig. 2 as taken Fig. 6 is a diagrammatic illustration of the systems control unit showing the various parts thereof.

A hydraulic Windshield wiper system embodying the instant invention is illustrated in Fig. 1 and contemplates the use of a pair of wiper units II and I2, a control unit I3 and a speed control valve I4. Fluid underpressure is admitted to the speed control valve I4 through a line I5 where it is metered for transmission through a line I6 to the control unit I.3. From the latter device, a line II supplies iluid to the window Wiper unit I I and a line I8 supplies fluid to the Window wiper unit I2. Both wipenunits are connected by a line I9 which transmits iluid therebetween, and fluid from each unitis exhausted through the control unit I3 to a line 20 which carries it to a reservoir (not shown) From the speed control valve I4, `a line 2l is connected into the line I'I feeding thewwiper unitII which provides a bypass for metered fluid from the downstream side of the speed control valve I4 around the control unit I3. "t 't y With thesystem just described, fluid under pressure is directed by the, control unit I3 alternately to the hydraulic motors 22 "and 23 of the wiper units II and I2, respectively,in a manner such that their wiper blades 24 and 25 are moved back and forth across sector areas of the windshield 2'6 to maintain the same clear of the elements and provide clear visibility through the windshield. t i

As is more fully described in a copending application, Serial No. 529,964, iiled April 7, 1944, now Patent No. 2,516,594, issued July 25 1950, by Howard E.\Rose, the hydraulic motor 22 comprises a cylinder 2l (Fig. 5) `in which a doubleacting piston 28 is operative.` The Ylatter element is provided on a portion of its external surface with a rack 29whi`ch is meshed witha pinion 30 xed to a splinedshaft 3I on which a windshieldwiper arm`32 is carried. Located within the piston 28 is a double-acting relief valve 33. The unitis also provided within its end connections 34 and V35 with ldashpot check valves 36 and 31, and the unit is supplied fluid through the lines I'I and I9 to move the piston 28, as will be described later. .Y

Sincethe hydraulic motors 22 andl 23 are identical with the exception of their connecting lines and arrangement in the system, onlyone will bedescribed. t l

The control unit I3, which directs the flow of fluid to thehydraulicmotorsZZ uand 23in a manner toreciprocate the wiper blades 24 and be treated here only brieily to the extent necessary to describe the function of, the unit.

As previously stated, high pressure uid is ad- Y CII mitted to the unit through the line I5, This line in turn is connected to a valve cavity 39- by meansl of a conduit 40. Within the cavity 39 a sliding valve 4I is operative. This valve, termed a double-acting relief valve, is biased to its neutral position by a spring '42., but is otherwise hydraulically' operated. Through its operation, a second sliding valve 43, known as av pilot valve, is controlled. This valve is entirely pressure operated and functions in a valve cavity M. A third sliding valve 45, described as a directional valve, moves within a` cavity,` 46 and controls the flowv of highv pressure iluid to either line I'I or l il depending upon which motor is Yto receive it. Within a Valve cavity 4l., a locking valve 48 is biased to its illustrated position'by a spring de.

'Il'he lines Il and I8- are connected with the valve cavity Q'I by. two conduits 5I and 52, respectively, and the exhaust linefZI) communicates with the 'cavity 39 by'meansjoi` -aconduit 53. Each ofy the. valve cavities has interconnecting conduits. Also, the various valves have reduced sections which permit a flow of fluid around the valve. The points ofentry 'of the various conduits into the valve cavities form ports which are opened and closed depending on the particular section Yof the valve moved over them. Conduits are also provided to apply pressure to the end sections of the various valves to effect their movement in their respectivecavities.

Although the control unit I3 .directs the flow of iluidfto the Wiper units.' itis incapable of controlling the speed at which they. operate. This function is. performed by 'a speed control valve IAIy which haslfor an,additional'purposethe automatic parking of the wiper blades. The rstobject is accomplished by controlling the rate of ilovv of iluid admitted to the control unit I3, and the second by automatically bypassing fluid under pressure from the metered sideV of the' speed control valve around the control unit i3, into the Wiper line I1.

As illustrated in Figs. Z'to 4,l inclusive, this device comprises a valve body 6I provided with a pressure inlet 62, a pressure outlet E3, anda parking outlet 64. Each ofY these portions of the valve body is tapped and threadedV to receive, respectively, the lines I5; I6 and 2I. The valvebody 6Iv is bored verticallynormal to the inlet and outlet openings to provide valve cavities in which both a metering valveassembly 15S-and a parking assembly 66 are inserted'.

The former assembly comprises a cap S1'- which is screwed into the valve body 6I, as shown. Movable Within a bore Gli-Within the cap 61 is a threaded stud 69 to which is splined' a thumb wheel 1I. The latter elementis secured on the stud '69 by means of anut 72. With this arrangement of the parts, the svtudrIS maybe raised or lowered to bear against a metering stem 13, car- 4 rying on its upper surface a pin 'I4 which is xed Within a central bore T5 in the stud l69. The

metering stem 'i3 is turned with an oblique surface 'i6 which seats against a shoulder 50 provided in the valve body. ICon'imunicating with a valve cavity 'l1 is a section 18 of the metering stein 'I3,`channel'ed at v'19, which, when the latter is raised, introduces an opening of progressively increasing cross-sectional area between the valve cavity ll and a valve cavity 8|. Thus, as the stud te is moved upwardly, an increased amount of uuid is permitted to flow from the inlet open- 7 ing 62 through a port 82, the valve cavities 3| and Tij, to a ports-3 connecting a valve cavity Sri with the outlet opening 63.

:Opposite the metering valve assembly 65,which is screwed. into the top of the valve body, is the parking valve assembly (it. This latter device comprises a cap 85, which is threaded at 86 to be inserted in the valve body 6I It is provided with a bore E-'I in which a compression springBS is retained. A ball valve- 89- is-seated in the top of the spring-83 andvis-biasedthereby-toseat-against a valve seat SI forming a part of van opening from a valve cavityglwhich, in: turn, communicates with another valve cavity r93. immediately above. The latter' valve cavity is connected. by a port' Se which communicates with theparking outlet 34 in thevalve body- GLI.

The port 3 3A Which connects with the pressure outlet' openingY E3 is connectedl With the valve cavity S2Y by: a' portv 9 lk which conducts,-` uidv from theoutlet 'side of: thev'alve to theparking outlet 64. Y i

Thel meter-ingvvalve Tie-.is opened. when the.. stud tiiis moved upwardlyby turning the thumbwheel H and is closed` againstpressurel byvscrewing.A it downwardly. vThe ball parking valve 89, on the other hand, is biased. to itsv closedposition by the spring 88 and isopenedbyfdownward movement of the meteringstem 13. Inthis case, theball 8,8 ismoved at a selectedA point ot travelof .the metering steml 'iby an. extension. 5'6 thereof.

Operation For the purposefof describing itsoperation, the system willbe assumed tope-stopped after. apre.- vious use.' In this condition, the' Wiper bladesZ-,tI and l.2l-l. will occupy parked, positionsV opposite to those illustrated-inFig, l, andY thelentiresystem will be considered as being lled Withgfluid. Fur,- ther, the various valves of the control,A unit. I3, with the exception-oi thelockingvalve-,will occupy positions opposite to those illustratedinlFig. 5. .As asV further aid; to thedescription of the systems operation,` cpiantitative;y fluid.V pressure valvesv will be used althoughfitvisjto'beexpressly understood Vthat the system is not to be limited to any particularoperating pressureor pressures, nor to .any particular,..pressureexerting medium,

' vl/Tvhe'n' itisdes'iredto Lplacethesystemdn. operation, high .pressure-'fluidWhichQ isinepressed ,upon the` system. fromaproper source throughthe lineV I5 is admitted tdtliasysteniby opening. the metering valve of therpeedcentrelunit;` The opening or. this vaiyegis, acccmvlisheo. by turning the thun'ib Wheel` 'I L in `a, counterclo tvisgewdirection, and the rateoiv oyyoijiluid paA ng irorn;tl,ie inlet to the` outlet,v connection oithismvalve around the metering sectionV 'M of* the metering valve is controlled bythe cross-sectionalarea oiithe channel 'it which is open. Erom the speed control valve Ill, meterediluidis Atransmitted through the line Iito thercontrol unit |37.' From this point, and by starting the operating cycle so as to conform to the illustrated positions of the valves 4|.

43, 45 and 48, highpr'essure fluidis transmitted through thelconduitAO, :and through the various valve cavities and` communicating vconduits to the left ofthe-flock `valve ,48 which moves it against thecompressive forcesof the spring 49 `to move the valves recessed portions into coincidence `with the ports of the conduits 5| and 52, respectively. Upon this operation, the control unit is 'released from its locked position and high pressure fluid can be ported to either of the lines orl by the control unit... f f

At the timehigh pressure fluid is acting on the lock Valve 4B,it is also acting against the left end section of the relief valve 4| where it acts against the forces of the spring 42. `Since the pistons of the hydraulic motors 22and 23 are moved to their extreme right hand positions, pressure of the fluid through thefrline |`|-to the wiper unit builds upto a valuexoi` approximately 450 pounds per square inch, which is .equivalent` to the active forces of the lspring 42. Since thispressure'is sufcient Vto 1ove rcorne the action of the spring 42, therelief valve is moved to the right, andfluid is ported to the right of the pilot valve 43 moving the same to theleft. As the pilot valve 43 is movedwto theleft, high pressure fluid is ported against the directional valve 45 to likewise move it to the left, Since fluid from the pilot valve to the directional valve is restricted in its iiow, as by having the middle land of the pilot valve only partiallyguncover the pressure port, as shown, the valve 45 moves more slowly than does the valve 43, and, accordingly, a full stroke of the valve 43 is assured. As the directional valve is moved to the left, high pressure is ported into the line I8, and the line is connected with the low pressure line 20, causing the pistons of the hydraulic motors 22 and 23 to moveto the left and reverse the wiper-stroke. As soon as this occurs, the double-acting relief valve 4|,is no longer pressure actuated, and the same ismoved to its neutral position by the spring 42. Under assumed conditions, 1 the `maximum operating pressure is approximately 400 pounds per square inch, which is insufficient to shift the relief valve 4| from its neutral position, the spring 42 being selected to require a pressure of 450 pounds per square inch to move the valve from its neutral position.

Sinceboth of the double-acting valves 33 of the hydraulic motors 23 and 22 are set for operation at 250 pounds per square inch, `there is at presn sure drop across the two `approximating 500 pounds per square inch. Further, the piston of thehydraulic motor 23 reaches its left endposi tion before the piston of the hydraulic motor 22 reaches its extreme end position. This causes the fluid to flow through the relief valve into the line I9, moving the piston of the motor 22 to its extreme left end position. The operating pressure of 400 pounds per square inch, however, is not suiiicient to flow through the two relief valves of the hydraulic motors 23fand 22, since both of them are in series and oifer a combined pressure drop of 500 pounds per square inch. Hence, fluid pressure in the line I8 builds up to a value of 450 pounds per square inch, which is sufficient to operate the relief valve 4|, and the entire sequence of operation is repeated with the valves of the control unit I3 and the pistons of the hydraulic motors 23 and 22 moving in an opposite direction to that described. Thereafter, and under the control of the control unit I3, high pressure fluid is directed alternately to the lines il and I8 and the wiper blades 24 and 25 are continuously moved over the windshield 26.

,When it is desired tofstopthe system and also ,to move the blades l'24Tand 2 5 to a selected parked position, themeteringvalvej ofthe speed control unit I4 is closediby turning the thumb wheel 1|;in a clockwise direction. r l i 1` As the thumb wheel 'His closed; the metering stemf|3 is moved downwardly and at a prede.- termined distance in` its travel, an extension 9S thereof presses against theball valve 830i the valveassvembly.i, SuchY action causes the valve 89 to open againstthe forces of the valve spring ,33 and fluid flows from the metering valve into the'ports 33 and 95,around the parking valve 89, through the portv 94, and into the line 2|, which is connected to the` line serving the wiper unit ||.l If, at this time, the control unit |3`is porting high pressure fluid into the line l'i, sufficient pressure will be built up therein to cause alrever'sal ofthe double-acting'relief Valve 4| within'the control unit I3. Fluid will then be directed from the pressure outlet of the metering valve, through the control unit |3, to the line I8 to cause the motors 23 and 22 to move the blades 24 and 25 tothe right. At this: time, the control unit j|3 has been conditioned to port the line I1 to the return line 20. Also, since the metering valve is being closed further during this time; sufcient pressure is not available in the wiper line. lato` c ause the control unit to effect another reversal ofthe wiper units; hence,

r the wiper blades 24 and 25 remain in this parked position because continued turning of the thumb wheel 'causes a complete closure of the metering valve, and pressure is cut olf entirelyl from thel wiper system.

Immediately Vupon closure of the metering valve, pressure is` cut oli` from the system, and the compression spring 49 is operative to move the lock valve 48 to itsl extreme left hand. position. `',Ihisjcloses'the portsof conduits 5| and 52, trappingiiuid under pressure in the system above the control unit 3 and providing a hydraulic lock for thewipe'r blades in their parked position.

Whilewa particular embodiment of the invention has' been illustrated and described. it will be apparent that the invention is susceptible to other modifications or changes, such changes or modifications to] which the invention is susceptible are to be .considered covered as if described, and the invention is to be limited only by the appended claims.'

What is claimed is: '1. In a control mechanism for controlling a reversiblefluid pressure-operated motor and for parking the same 'in a predetermined position: a' reversing'mechanism having a high pressure inlet passage and a low pressure outlet passage, having a first working line and a second working line for opposite connection into the motor; having valve mechanism for rst connecting one working line with the high pressure inlet and the other with the low pressure outlet, and then reversing said connections, there being fluid pressure-operated reversing valve means for causing such reversal, which valve means is oppositely ported to the two working lines to be shifted when the pressure in the working lines attains a predetermined differential resulting from obstruction of flow therein as when the motor is stopped; a speed regulating valve in one of the pressure passages to the reversing mechanism, the same being a throttling valve to adjust fluid iiow through such passage whereby to regulate the rate of pressure fluid flow into the Working lines so that the speed of the mo- 7 ltor may be changed; a bypass connectionk from the pressure passage having the throttling valve, to one of fthe working lines, means normally closing the bypass connection; means associated with thethrottling vvalve to open the bypass connection when the throttling Vvalve is moved to a predetermined throttling position, to

restrain movement of the motor from parkedV position.

4. In a control mechanism for controlling a reversible fluid pressurefoperatedmotor and for parking the same in a predetermined.v position:

a reversing mechanism having.l a high` pressure inlet passage and a lowpressure outlet passage, having aiirst workingr linerand a second working line for opposite connectionv 'into theA motor;

having valve` mechanism for iirst: connecting P' one working line with the high pressure. inlet andthe other withY the low pressure outlet, and then reversing said connections,` whereby the motor may be operated back and forth; a control valve in one pressure passagethat can be closed' to cutA the pressure flowin such passage 'whereby to stop. the operation; and means to lock .working line pressure conditions to restrain iow therein and hence to lock the motor in pre.-

determined positioncjompri`sing a` locking valve to block at least oneof said. working lines, and means to opensaidvalve. when the control valve is opened.

5. In a. control mechanism for controlling a reversible fluid pressure-operated' motor. and for parking the same ina predetermined` position: a

reversingmechanism havingahi'gh pressure inlet passage andV a low. pressure outlet. passage, having a rst workingline anda secondworking line for Opposite connection into the motor; hav.- ing valve mechanism for rst connecting. one working line with the high pressure inlet and the other. with the low pressure outlet, and. then reversing said connections, whereby the motor maybe operated back and forth; aV control. valve Y i in one pressure passage, thatcan beclosedtocut 8 the. pressure` flow in. such passage whereby to stop the operation; and means to look working line pressure conditions to restrain flow therein and hence to lock the motor in predetermined position, comprising a locking valve to blockV at least one of said working lines, and: means to open said valve when the control valve isV opened, comprising diiierential force' means' including a pressure chamber connected to the pressure passage having the control valve.

6. In a control mechanism for controlling a reversible fluid pressure operated: motor, such as for windshield wipers, and. for parking the motor and locking'V i'tl in parked position: the combination ofk a controlv uniti having a high pressure inlet, atlow pressure outlet, arst'working fluid line, a second working fluid line, and a reversing uid valve mechanism having means to connect the two working lines respectively to the inlet and outlet, said .means having a fluidi pressure-operated device. responsive to the increase in fluid pressure in the high pressure working. line caused by resistance in the high pressure working' line to reverse the connections of the two working lines withrespect tothe inlet and the outlet; a throttling valve in the high pressure inlet to regulate the pressure ow of fluid to the reversing control so as to regulate the pressure flow in the working linesand hence thek speed of the'motor; a bypass connection to conduct high pressure to one working line, means normally closing the bypass connection, means to` open the bypass connection when the throttling valve is closed dov/n to a predetermined throttling position, whereby to insure adequate pressure in such working line to reverse the reversing fluid valve mechanism despite throttling of the pressure in the inlet to below such reversing pressure; and means automatically operated by full closure of the inlet to'close both working lines.

RUDOLPH FREEDMAN. JOHN E. DUBEL REFERENCES CITED The following references are of record in the iiieof this patent:

UNITED STATES PATENTS Rappl June 20, 1944 

